In a wireless communication system, a wireless signal (e.g., in a form of an electromagnetic wave) transmitted by a transmitter can undergo attenuation as it propagates through space. For example, a receiver (e.g., a mobile device) can receive a wireless signal transmitted by a transmitter (e.g., a base station). The difference in the signal strength (e.g., in terms of power or energy) between the transmitted wireless signal and the received wireless signal strength can be referred to as path loss, which represents the reduction in power density (attenuation) of an electromagnetic wave as it propagates through space. Path loss can be used in analysis and design of a link budget of a telecommunication system.
Path loss may be due to many effects, such as, free-space loss, refraction, diffraction, reflection, aperture-medium coupling loss, and absorption. Path loss can be influenced by terrain contours, environment (e.g., urban or rural, vegetation or foliage, and the like), propagation medium (e.g., dry or moist air), the distance between the transmitter and the receiver, the height and location of antennas, and other factors.
As such, for a same transmitted wireless signal, the received signal strength can be different depending on the locations of the receivers as the transmitted signal can undergo different path losses before reaching the receivers. The received signal strength can be measured or calculated. The path loss can be calculated, for example, as a difference between the received signal strength and the transmitted signal strength.
Calculation of the received signal strength and/or path loss can be typically referred to as prediction, without requiring actually transmitting the wireless signal. In practice, calculation of the received signal strength and/or path loss typically involves approximations. For example, the received signal strength and/or path loss can be predicted using statistical methods and deterministic methods. Statistical methods (also referred to as empirical methods) are based on measured and averaged received signal strength and/or path losses along typical classes of radio links. Deterministic methods are based on physical laws of wave propagation. Ray tracing is an example of the deterministic method. There are commercial tools for received signal strength and/or path loss prediction, such as VOLCANO software by SIRADEL.